Who would benefit from a Cochlear Implant?
Children or adults who have a severe to profound sensori-neural hearing loss do not benefit from even the most powerful hearing aids. Such patients require Cochlear Implant Surgery in which a small implant is placed under the skin behind the ear. With the help of the implant, they can hear all sounds.
Infants born with a hearing loss have a delay in their hearing, speech and language development. The degree of delay or non-development correlates with the degree of hearing loss. Babies with mild loss will develop a mild delay, but those with a severe to profound loss will usually develop very poor listening, speech and language skills, even if they wear powerful hearing aids. After Cochlear Implantation, they learn to hear and speak, just like normal hearing children. Such children have grown up to finish school and college/university, and live near normal lives.
What is the ideal age for Cochlear Implants in Children?
Establishment & development of the centres & neural pathways in the brain for hearing, speech and language takes place after birth as the child listens to all the sounds in his/her environment. In a child that does not hear, this development does not take place. Also important to understand is that this ability or ‘plasticity’ of the young brain to develop is lost by the time the child is between 5-7 years of age. For this reason, it is of utmost importance to have an early diagnosis of hearing loss and to start treatment as early as possible.
Children diagnosed late and fitted with hearing aids or Cochlear Implants tend not to do as well as those diagnosed early and fitted early in life. The ideal time for hearing aid fitting is as early as 3 months of age. And for Cochlear Implant surgery is 6-12 months of age.
Children implanted before the age of 12 months tend to develop almost like other hearing children. Most develop near normal hearing and speech.
Cochlear Implant Program at Sir Ganga Ram Hospital:
World over, Cochlear implants are being implanted since nearly 40 years in patients of all ages. The Cochlear Implant Program at Sir Ganga Ram Hospital was established in 2001 by Dr. Shalabh Sharma and has completed over 1000 succesful implants. Our youngest implantee is 8 months, and the oldest is 86 years.
Tests before surgery:
Hearing tests and Imaging tests are necessary prior to considering implantation.
Hearing tests confirm the type, site and severity of hearing loss. Children with a loss of less than 70dB are usually fitted with hearing aids, while more than 70dB are planned for Cochlear Implantation. Unaided audiometry, Aided audiometry, BERA, ASSR, Impedance audiometry and OAE screening are some of the tests.
Imaging tests are a High Resolution CT scan of the bone of the ear and an MRI of the Inner Ear. These tests show the structural anatomy of the Inner Ear, the Auditory nerve & the Brain. Presence of an abnormal Inner Ear structure can change the choice of implant and electrode, as well as the prognosis. Presence of a thin hearing nerve can influence the side to be implanted. This is a decision taken in consultation with the audiologists & radiologists.
Cochlear Implant Team:
Some children would require evaluation by a Developmental Specialist, Child Psychologist, Pediatric Neurologist, Pediatric Opthalmologist, Occupational Therapist, Pediatric Cardiologist, Genetic Specialist etc. All these specialities are well represented at Sir Ganga Ram Hospital, and Dr. Sharma would refer to the specialist/s whose opinion is required. This would help in identifying any issues the parents or Implantees may face during or after implantation.
The process of Cochlear Implantation
After the decision is taken to implant, certain routine blood & urine tests are necessary prior to surgery.
The Surgical Package at Sir Ganga Ram Hospital includes a 2 or 3 night stay at the hospital. Admission is usually on the day of the surgery and discharge after 2 days.
During surgery, after the implant has been inserted, the computer aided telemetry is carried out by the audiologist to confirm the device is fine and to record the responses from the brain. This recording during surgery helps in setting the parameters (MAP) of the processor at the time of ‘switch-on’.
A head bandage & single suture (stitch) are present and these are removed between 7-8 days after the surgery.
‘Switch On’ of the Implant is when the child wears the outer Processor and starts hearing sound for the first time after surgery. This is usually accomplished by the 8th-10th day after surgery.
After Cochlear Implantation
Children and adults require periodic ‘mapping’ of the device by the Audiologist. The minimum (threshold) current level at which the sound is ‘just’ heard & the maximum (Uncomfortable) current level at which the sound becomes uncomfortable is determined manually for each of the electrodes and then the processor is programmed accordingly.
In the first few months after surgery, frequent ‘mapping’ sessions are required, as the current levels required for stimulation will change with time as healing takes place. Later on, ‘mapping’ sessions will be required once in 6 months or longer, for which visits to the clinic will be required.
AVT or auditory verbal therapy sessions are necessary in children to help them get the maximum benefit from the implant. AVT helps the child to learn to listen to sound, understand sound and subsequently go on to develop speech and language. Frequent AVT sessions with the AVT therapist is a must, and for patients who live far away from the centre, sessions by skype are also possible.
Children who have been implanted early are attending normal schools. Ayush, the first child in our program to be implanted in 2002 at the age of 2 years, has now been admitted to an engineering college. Most of the implantee children who were implanted at an early age are in normal schools/colleges and doing well.
In India, approximately 6.3% of the population suffers from significant hearing impairment. This equates to around 80 million people, which includes children and adults. 3-4 per 1000 children born suffer from severe to profound hearing impairment, which is hearing loss of more than 70dB. This is significant enough to usually warrant a powerful hearing aid or in most cases, Cochlear Implant surgery.
In a developing country like India, most of the population suffering from hearing loss do not have access to or cannot afford hearing aids/implantable devices that can help them overcome their handicap.
It is a cause of concern if a child does not seem to pay attention to the sounds around him or to his family calling out his name. If a baby does not startle to loud noise or if a child does not pay attention in school. An adult is suspected to have a hearing loss or when an elder seems to withdraw from family conversations, then, hearing tests can be carried out that can identify the type and severity of hearing loss, even in someone as young as a newborn. These tests should ideally be carried out at centres that specialize in hearing testing, especially in the case of young children.
Cochlear Implants are electronic medical devices that are implanted inside the body (under the skin behind the ear). These implants provide a sensation of hearing to the person. Cochlear Implants have been around since the 1980’s, and have helped about 600,000 patients hear again.
The cochlear implant has an external processor which is worn behind the ear. This has a microphone which receives the sound and processes it into a digital form. These signals are then passed into the inner unit (implant) thru the intact skin in the form of FM radio waves. This activates the electrode inside the cochlea, and the person starts hearing sound. The outer unit or processor has a rechargeable battery. The implant is activated by the energy from the processor.
Children, as young as 6 months, have been implanted in a few centres around the world. Generally, the younger the child, the better the results. The practice all over the world is to try and implant children at about one year of age or earlier.
In adults who have lost their natural hearing (post lingual hearing loss), cochlear implants generally have excellent results. However, the duration of hearing loss does have an effect on the results. If the duration is more than 15-20 years, then it can take a bit longer for the person to learn to use the implant efficiently.
Any person, child or adult, who has a severe to profound sensorineural hearing loss and does not get adequate benefit with hearing aids.
Hearing (Audiological) tests and CT/MRI scan (Radiological tests). Hearing tests that may be required are Impedance audiometry, OAE, ASSR, BERA, Unaided and aided audiometry.
Cochlear Implant surgery is recommended for children over 6 months of age and also adults who have been hearing earlier and have now lost their hearing due to infection or injury etc.
The patient undergoes an x-ray of the implanted ear the day after the surgery. The bandage and sutures are removed on the 7th day after surgery. The ‘switch on’ of the device is when the patient wears the outer unit (processor) for the first time. This is usually on the 8th-10th day after surgery. At the switch on, the patient starts hearing sound immediately.
The audiologist ‘maps’ or programs the processor to give the full range of sound across all frequencies.
The child will start hearing immediately after the switch on of the implant. And from this day onwards the hearing centres in the brain will start developing and will comprehend sound.
A child needs to have a period of hearing before he or she can learn to start speaking. Babies may be born deaf, but never dumb. A child would normally start learning to speak about 6-12 months after the surgery, but this depends on many factors like age at implantation, IQ level, single ear implant or bilateral (both ears) etc.
Involvement of parents is of prime importance at this stage.
A good speech therapy centre has an audiologist, auditory verbal therapist (AVT), child psychologist, occupational therapist etc. The audiologist and the AVT therapist would normally monitor the progress of the child.
After the cochlear implant surgery and speech therapy sessions the child will be able to attend a normal mainstream school and grow up like any other child. Children who were implanted 30 yrs ago have already graduated from college and pursuing their respective professions.
Copyright ©2021 drshalabhsharma.com. All Rights Reserved | Powered by: DPI INFOTECH